Study on Combustion Improvement of Low-Grade Bunker Fuel Oil by Auxiliary Hydrogen Injection

第一年（2001年），研究人员主要集中在低品位船用燃料油引起的燃烧问题和喷氢系统的建设上。调查研究的结果被总结为在几个国际会议上发表的实验报告。低标号燃料带来的问题有两个方面；一是它的点火延迟时间较长，几乎是普通bfo的三倍，另一个是它的燃烧速度较慢，永远不足以使喷雾火焰上升到喷射喷嘴。在这种情况下，通过与其他研究人员的讨论，也获得了有关氢气喷射系统的重要信息。在第二年（2002年），氢辅助燃烧的特点进行了详细的视觉研究。揭示了氢的助燃特性。在喷油后刚喷氢时，有时氢的着火发生在喷嘴尖端附近，由于氢火焰的快速传播，点燃后燃料喷雾立即被发光火焰覆盖，大大缩短了总燃烧时间。为了减少PM的排放，PM被认为是燃烧的最终未燃烧产物，在燃油喷射结束之前注入氢气。结果表明，氢/空气混合物的快速膨胀及其较高的燃烧温度所引起的扰动有助于还原剂完全燃烧并产生较少的烟雾。总的来说，本研究在概念和验证两方面都取得了成功。

In the first year (2001), researchers mainly focused on the investigation of combustion problem caused by low-grade bunker fuel oil and the construction of hydrogen injection system. Results from the investigation study were summarized as experimental reports presented in the several international conferences. The problems with low-grade fuel resulted in two aspects ; one is its longer ignition delay that has almost three times as long as normal BFOs and the other is its slower burning speed that is never enough for spray flame to go up toward the injection nozzle. Important information about hydrogen injection system was also obtained in such occasions through discussions with other researchers.In the second year (2002), characteristics of hydrogen-assisted combustion were visually investigated in detail. Unique feature of combustion promoting effect of hydrogen was unveiled. When hydrogen is injected just after the fuel injection, ignition of hydrogen sometimes happens in the vicinity of nozzle tip and after the ignition fuel spray was immediately covered by the luminous flame because of rapid propagation of hydrogen flame, which reduces total combustion period drastically. To purpose reducing PM emission, which is thought to be final unburnt products of combustion, hydrogen was injected just before the end of fuel injection. The result showed that disturbance caused by the rapid expansion of hydrogen/air mixture and its higher combustion temperature helped the reduced to burn completely and generate considerably less smoke.On the whole, this research was successfully concluded on both conception and verification sides.